[Practical data on digestive tract oncogenetics].

Inherited conditions predisposing to cancers have long been recognized. Specific medical recommendations have more recently been proposed to avoid the development of advanced cancers in such high-risk families. The identification of the first genes involved in monogenic dominant cancer-prone conditions have opened the ways to their predictive diagnosis in asymptomatic members in at-risk families. The development of such procedures has required specific involvement for clinicians and molecular geneticians. The example of familial predispositions to colonic cancers has been chosen to illustrate the practical issues, and to help the physicians in charge of at-risk families to offer their patients an access to these emerging possibilities in cancer prevention. A table summarizes the practical issues requested to refer a family and initiate the procedure of molecular testing.